~te forms and how they are different

[GoldCoinLover]

You need to be able to create them youself, by starting from simple Japanese then working your way up. There's another sentence there that you can probably already say based on your ability so far:
"I don't need a plastic bag"
Plastic bag = fukuro
Need = irimasu
Don't need = irimasen
Therefore "I don't need a plastic bag" is "fukuro ga irimasen". I say this on a near daily basis in Japan

What is the plain form of iri? Iru?

 

[The7thSamurai]

What is the plain form of iri? Iru?

You got it!

One thing to remember about "iru", "to need" (different kanji to the other "iru") is that it's actually a Yodan verb, despite it looking like an Ichidan. There are a few other verbs out there that look like Ichidan verbs (i.e. end in either "iru" or "eru") but are actually Yodans. Another one is "kaeru" (to return) - looks like an Ichidan because it ends in "eru" but it's actually a Yodan, so instead of saying "kaemasu" you actually say "kaerimasu".