Note: JPG doesn't support transparency. Use PNG, .TIFF or .GIF instead
You could use Paint.Net that is free or there are online progs that you upload image to edit.
Working with layers Paint.NET ClickHere
In my old ancient paintshop pro 7 this is what I do:
on Top tool bar click on 'Layers' and choose 'promote to Layer'
click on the 'Magic Wand' tool
put cursor on the background part of image that I want to get rid of and leftclick
it now has flashing dotted lines round the separate parts.
press delete on keyboard.
rightclick on image so that nothing is selected (flashing dotted lines no longer there)
I am left with a rose surrounded by a checkered background.
File - Save As - and choose .png as file type