So you have PES 2017 installed and running. Have you installed the ICUP 6 DLC and EDIT files? (contains all the changes we made for the last full tournament). First you should get those working in PES by pitting them in the correct folders as instructed and using Boris's DPFileList tool to make PES load them in.
To edit the DLC, use a CPK extractor (there's some on the wiki, can't hurt to virus test on VirusTotal.com) to unzip the file structure. Some files are encrypted with zlib (more decrypted on the wiki, but check for dodgy ones!! If you're fine with CLI there's a clean one the 4CC made) but the kits should be fine. implyingrigged has a page on it, basically you find the folder full of kit textures, find the ID of the one you want to replace (I think we're restructuring IDs soon so just pick one high on the list like /2hu/) and replace the .dds texture. I use GIMP to open a .png and save it as a .dds, the wiki tells you the export settings. The other texture handles things like shinyness (for that sticker material) so probably just leave it all that exact green. Then use the CPK tool to repackae that filesystem, put it in the DLC folder and re-run the DPFileList tool to load it into PES.