title says it all ^^^^^^^^^^

first, download inkscape. its a free program that alows you to make svg files. if youve ever used photoshop (or more preferably, adobe illustrator) than using inkscape wont be too hard.

theres a warlight wiki that talks you through the limitations to maps and such, as well as a link to activate the 'design maps' tab

Here's a thing I made a while back:
https://www.youtube.com/watch?v=8PtjYWuh8qw

I know it's not super informative, but you can pm me if you need some more help.