ideas in the colle system

You probably need just the basics.

First... Brief history lesson. It's older than many know. The Colle was was named after Edger Colle who used it frequently in the 1920s-30s and had many brilliant games using it, making the opening popular. That said, is was being played in the mid 1800s

Opening moves are 1.d4 2. Nf3 and 3.e3 with two variants . The Colle Zuckertort and the Colle Koltanowski

The Zuckertort var.. (named after a famous player Johannes Zukertort) entails playing b3 and Bb2

The Koltanowski Var (named after George Koltanowski who was a good friend of Edger Colle and after Colle's death in the mid 1930s, played the opening in his honor also and had very good results . The Koltanowski entails playing c3 (not b3 & Bb2)

IMO.... It's important knowing the history of the openings you are playing!!! Because you will miss key ideas that were used as the opening evolved. (these ideas you can implement into your game)  The Colle Zuckertort var was being played in the mid 1800s One of the key ideas being employed was what I'd call "A Supported Stonewall Attack" (***side note The Stonewall attack was a popular opening at the time)

About mid 1890s people started playing what was deemed an accelerated version

Then after World War One, Chess masters got the idea of pushing the e pawn to e4

Edger Colle burns the midnight oil, and the rest is history.

Practical advise. Pick and stick with one variation. There are nuances when Black plays 1...d5 that are specific to the variation. At First... priority no#1 Learn Anti-Colle lines. When Black plays 1...d5 about 50% of your games will be an Anti Colle or a Chigorin. The good news is both defenses with the best play, gives Black equality and nothing more. You will be playing these position a lot and will becomes much more familiar.

After you climb up the Elo ladder... you can not play the Colle in wrote fashion. You will have to deviate. Black will essay Indian Defense where you will have to adjust the opening. Or.... your opponent will play known lines where you will struggle if you play your standard Colle moves.

Example:

Finally... Pick a variation of the Colle that suits you. People will say the Zuckertort is better than the Koltanowski. IMO that is not a true statement. Both are equal.