Can somebody help me with acoustical guitar strings? i just started to play and my guitar came with some medium strings that are killing me. i do understand that pain will be there at first and i can live with that. however my issue is that since im a newbie after practicing for longer than 30min i cant seem to press hard enough to get clean sounds .
i have a Washburn Dreadnought and ive been told to look for Lights. ive been looking at GC for some new strings and i found Marting Co. $4.99 and D'Addario $12.99 both have Extra Lights. 10,14,23,30,39,47. the difference was the coating Martin has none and the D'Addario have their EXP coating.

my question is are the D'Addario worth it? and what does the coating do exactly? or if you have a better suggestions.