[reducing file size]

I am totally new to Affinity and I have recently joined a camera club where all digital images have to have a file size of 1600 X 1200 pixels.

My photos are much larger than this.

How do I reduce file size, please.

Thanks

[Reducing my dimensions to suit requirements (split)]

I am a complete newby to Affinity and have never used photoshop.

I have recently joined a camera club and they require their images to be 1600 X 1200 pxl . My files tend to be 6226  X 4270 for example.

How do I reduce my dimensions to suit requirements?