How do I use a custom pallet? And whenever I insert exGFX, the exGFX is garbled. Please help.
To insert a custom palette, go to File->Palette->Import custom palette and load the palette file that came with the ExGFX you downloaded.
If the ExGFX is garbled, my best guess is that you didn't insert the Map16 pages. Click on the item block in the toolbar and use the arrow keys to navigate to a blank (filled with little light blue cubes) Map16page ad press F3 to insert your Map16page. (The Map16pages that came with the ExGFX you downloaded should be in the same folder as your hack's rom.)
Once the ExGFX shows up properly, press F9 to save the Map16page into your rom.
If that's not your problem, my only other guess is that you didn't insert the ExGFX into your level. Open up the Super GFX Bypass window and choose the ExGFX file you want in either the FG3 (For foregrounds) or BG1 (for backgrounds) dropdown box.
I hope that helps.