start in the center---line up the designs---pinning them together so the match perfectly- then smooth the fabric out from them--your outter edges will have to be re-straightened-but your motifs should be lined up- problem with using panals is they are seldom printed exactly alike- and once fabrics have been pre-washed the wonky-ness really becomes apparent- in some cases it is better to forgo the prewashing part---but too late now- the only thing to do is line up the designs---but it may still be impossible-they may not even be the same size anymore- putting them together and pinning them will show you if their size is off too.
good luck.