Getting more with も and と

も is an inclusion marker. You can think of it like "too" or "also". Sometimes "even".

も is a particle that, similar to は, goes together with other already-existing particles. When も is used to mark something that would be normally marked by が or を, the particle is dropped and only も is left. With other particles, you just attach も after the original particle.

私も行く
I'll go, too (in addition to other people)

魚も食べたい
I want to also eat fish (in addition to something else)

学校にも行く
I also go to school (I go to other places too, but also school)
While も usually “hides” を, you might come across をも as well. It’s a bit uncommon and not worth thinking about, just don't be surprised when you see it. You can think of it as a more emphatic version.

も can be used with negative statements. Normally, it includes the given noun in the set of things that the negative statement is true for, but sometimes it does weird things because negation changes how logical inclusion/exclusion works. 

僕も食べない
I won't eat, either. (in addition to other people)

The particle と is also used to provide some “inclusion”, but it works very differently from も. It may look similar at an English translation level, but don’t be fooled. They are nothing alike.

と normally makes a list of things.

ジムとメアリーは来ない
Jim and Mary won't come.

と can also be used to mark someone the subject does an action “with”. Do not confuse this with で which might seem similar: the distinction is that と is usually used for people (who you do something with), while で is used for tools and things (what you do something with). 

私はヤンと勉強する
I study with Yan.

ペンで書く
To write with a pen (lit: “by pen”)

Sometimes で and と may seem interchangeable, but the nuance is a bit different. Compare the following:

みんなと遊ぶ
To play with everyone

みんなで遊ぶ
To play (together) with everyone

In English, the translation is effectively the same, but と in the first sentence implies the subject is playing with everyone as an additional group of people (so it’s subject + everyone else). In the second sentence, however, the subject is part of the group, and they are playing as everyone together (“everyone” includes the subject). It’s a very subtle nuance but it’s good to be aware of it.