Particle GA

ga-subject marker Links subject directly to following verb or adjective, or emphasis on a subject.
Ga is probably the most difficult particle to explain , so these are just basic usages.
ex. Dore ga shimashita ka. Who did it? emphasis on "who"
Shinohara-san ga Tōkyō ni ikimashita. Shinohara went to Tokyo. emphasis on Shinohara.
Anime ga suki desu. I like anime. Anime linked to the verb "to like"

Particle WA

wa-topic marker;subject marker. observable actions. Can be thought of as "As for (the)"
ex: Yamakawa-san wa nihonjin desu. Mr. Yamakawa is Japanese (As for Mr. Yamakawa, he is Japanese.)
Literal: Mr. Yamakawa wa Japanese is.