I think あります　means ‘to be’ or ‘to exist.’ It is used mainly when referring to inanimate objects.　ありません　is just the negative form: ‘to not exist’

As for the verb question, Japanese verbs have two parts. The first part is the root which says what the verb is. The second part describes when and how the verb actually happened. For example, the root of 入れる　is 入れ, meaning ‘insert’ or ‘fill.’ ました　is a verb ending meaning used to politely signify that something happened in the past. So when you put them together, 入れました means ‘inserted’ or ‘filled’ and is something you could say in front of your boss without being ashamed (since it’s a polite form).

You may be asking “how do you know what part is the root and what verb stuff to put at the end?” That’s a good question with a slightly less satisfying answer. There are many different categories of verbs and many different verb endings and a set of rules for combining different verb categories with different endings. These rules, like every set of language rules, have exceptions. Eventually, you will end up memorizing the categories and many of the endings and the exceptions, and by that point you will be a Japanese Master. But for now, I’ll walk you through this particular case, so you can see how it works.

1) Different categories of verbs have different “connectors” which you put between the root and the verb ending.
2) Each category of verbs has about 7 different connectors that can be used depending on the ending.
3) 入れる　is a member of the Ichidan verb category. You can guess this because Ichidan verbs end in ‘iru’ or ‘eru.’ But some not-Ichidan verbs also end in iru or eru, so you have to memorize the exceptions.
4) ました is of the ‘masu’ verb form (masu, mashita, masen – very useful. You will see them a lot.)
5) Verb endings in the ‘masu’ form always use connector #2
6) You “build” the verb by chopping off the last character, adding the connector and adding the verb ending.
7) Ichidan verbs actually do not have a connector #2, so you just chop off the last character and add the verb ending right to the root.

Thus: 入れる with the last character chopped off becomes 入れ、 then with the ending added becomes 入れました

Phew! Isn’t grammar fun? In any case, don’t worry if this is overwhelming. Japanese learning resources usually take this one step at a time, so you will be eased into it eventually. If you’re looking for an awesome resource about it, I’d recommend “Japanese Verbs & Essentials of Grammar” by Rita L. Lampkin. I have the 2nd edition c: