There are already a number of good jpeg's out there to download. 'Adam Souza', Wood Elf pitch is one of my favourites. But I wanted to create a pitch you could downloaded and modify easily. The excel file is available here. The pitch includes items for dugouts and a scatter marker. If you want to change any parts you can just open the document in excel and copy and paste parts to move dug outs or turn markers.
If you would like to change the background you just need to go into page setup and add you own tile set to repeat. By changing the image in the header. Also just incase you did not know *.xlsx can be renames to a *.zip and you can explore what is inside the excel file. Look under 'renamedfile.zip\xl\media\' and you will find the image jpeg you should be able to swap out.