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OP, unless you know exactly what you're doing, don't jump straight into manual mode.
Like many Anons here have already posted, start by playing around with the programs modes. If you jump straight into manual mode, realize that you will miss a lot of shots.
Canon sensors aren't exactly known to be best for low-light or dynamic range, so learn to live with the limits.
Best and easiest way to control exposure is by using a flashgun/speedlite. I shoot 99.9% with one even with my 6D even in full daylight conditions. Just allows me to control lighting much more.
Pic related.