The prince visited the Mants'ase Children's Home in Maseru, Lesotho.
"Festive cheer! Despite it being 32 degrees, someone gave out Christmas hats and inevitably one found its way on to my head," he wrote.
"All the children, orphaned for one reason or another, absolutely loved the hats and balloons."
Prince Harry was supporting the charity Sentebale which assists projects that work with disadvantaged children, many of whom have Aids or have become orphans because of the disease.
He was also photographed participating in the building of Mamohato Children's Centre.
This will give emotional and psychological support to young people affected by HIV and Aids.
The prince visited a Mamohato Network Club in Maseru and said: "These are children who have never had the chance to talk about their illness, and who had no idea that they were one of so many in their age group.
"It was really emotional watching them interact with each other. Some really outgoing chatty kids, others slightly overwhelmed, but all with huge smiles.
"This confirmed to me again that what we're doing is going to change thousands of children's lives, and hopefully save a generation."
Prince Harry also revealed his own love of photography and shared some images that he had taken.
"I have always enjoyed photography and the challenges that come with trying to capture the perfect shot, although privately I don't take many photos," he said.
"The best photos I have are in my head - I have some very special memories, mostly from Africa.
"But on this visit, I had the time and opportunity to be on the other side of the camera and take some photos in the stunning country of Lesotho for my charity, Sentebale."
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Vokes is now tied to the Turf Moor club until the end of the 2018-19 season.
"My massive goal is to do well at club level and play at the Euros in the summer," Vokes told BBC Radio Wales.
The 26-year-old, who has six goals in 37 games for his country, has been with the Clarets since joining from Wolves in July 2012.
He has scored 31 goals in 137 appearances in all competitions for Burnley, with a total of 64 in 300 career games.
He has netted five times in 27 games for Sean Dyche's side this season.
"It's great to put pen to paper, I've been very happy at Burnley, it's a club I've found a home at in the last few years," he said.
"We are concentrating on pushing for promotion and that was a massive factor in signing the new deal, the belief I have in the club.
"Promotion is a big aim and I think we've got the squad to do that."
A spot in Chris Coleman's 23-man squad for Wales' first major football tournament since 1958 this summer is another priority.
"I'm not guaranteed a spot, it's never a given or something I'd take for granted. You need to be playing well for your club to be picked for your country," Vokes added.
"I need to do well this season and that gives me the best chance of going to France and forcing my way into the team."
Vokes' 2014-15 campaign was hampered by a cruciate ligament injury but has suffered no problems since having surgery.
"Three-and-a-half more years shows faith from the club in me and they stood by me with my injury," he said.
"I'm over the injury, it's behind me now, but the club were great with me.
"Playing week in and week out has helped."

Dorothy Cooper was seriously injured when a man allegedly jumped into her vehicle and drove over her in a car park in Royton, Oldham, on Wednesday.
Paul Anthony Moore, 45, of no fixed address has been charged with wounding with intent, dangerous driving and motoring offences, police said.
He was remanded in custody to appear before magistrates in Manchester later.
Mrs Cooper got out of her white Hyundai i10 when she was told there was a problem with it, witnesses told Greater Manchester Police.
As she was checking the vehicle, a man allegedly jumped in and drove over her.
The car was found about three miles away in Buersil Avenue, Rochdale.
Photographs showing a festive Prince Harry have been released, to mark his support of a charity helping children affected by HIV and Aids.
[NEXT_CONCEPT]
Striker Sam Vokes is aiming for promotion and a place in Wales' Euro 2016 team after signing a new contract with Burnley.
[NEXT_CONCEPT]
A man has been charged  with wounding a 76-year-old woman who was run over by her own car in a suspected carjacking.