You will need to download FM Filetools to make easy seamless backgrounds
click here to download the zip file
Choose your pic you want to make into a background
Go to effects and choose FM File tools - seamless tile
click apply then go back again to the seamless tile effect and this time tick the box 'vertical' and click apply
you can then also make this into a nice muted background
by adding a new raster layer
have your colour palette set to white
choose flood fill and change the opacity
I set this one at 80%
fill the layer merge all layers and save and there you have your background
