Yup, however つまらない or the more colloquial version つまない are more common to say for present tense I've found. I've also heard 退屈 used more as a Na-adjective more than a する-noun.

Yes, it does! :)　Watashi ha(wa) ima taikutsushiteimasu means "I'm bored now."

mason and Brian are correct. Taikutsu shiteiru = be bored (present tense) I'm bored. = watashi ha taikutsu shiteimasu.(taikutsu desu.) I was bored. = watashi ha taikutsu datta. (past tense) --- be boring = ---ga tsumaranai. Ex. The movie was boring. = sono eiga ha tsumarana katta.

that is great ,learn together

Mason wrote "tsumaranai" or colloquially "tsumanai." However, be aware: If you say "watashi ha (wa) tsumaranai" you mean "I'm BORING" rather than "I'm bored." So you should say "watashi wa taikutsushiteimasu" or simply "tsumaranai" (without "watashi wa").