if you select any of the CSC, you probebly get a single .7z file which can be extracted with winrar, then you will get a .md5 file, just select that one from PDA, as per the guide of the same thread....GOODLUCK
I have not tested this to comment, but used 2.3.6, its very stable...
there are firmwares released after this also..like XWLA2, LA4 etc...
LOVE FOR ALL HATRED FOR NONE
Mine : Ph: SGS4 (OLD BL); ROM: latest SHOStock 4.4.2 + Jeboo's Z-pached Kernel
Wife's : Ph: SXZ1 (6903) Locked BL ROM : NUT's 14.2.A.1.136 [Root & XZDR][LB/UB]