Here's a link to the manual on Canon's website:
Canon T1i User Manual
Google "photography composition" and "rule of thirds". Also search for "exposure triangle". That should give you some good information.
#1: I would have gotten closer to the artists, maybe picking one out that was currently painting and making it a portrait. Art capturing art. This image is waaay out of focus (OOF, as the forum likes to abbreviate it). If you're using manual focus, I suggest switching to auto focus. The camera will do a much better job than we will. Our cameras aren't designed to be focused manually, although they let us try if we want to.
#2: Try not to cut off your subject. There's a graininess to the image that's off-putting. I suspect it's from post processing (PP). Overall, if those two issues were resolved, it's not a bad image; just a bit bland.
#3: This would have been a great image had the focus been right. Always focus on the eyes. It looks like the focus is mostly on the ruffles of the baby's shirt. I think you need to use a smaller aperture (larger f/#). Your image doesn't have any EXIF data, so I can't tell. If you posted the original file from the camera, I could get a better idea.
#4: Way too yellow and over exposed. Reading up on the exposure triangle will help you here. Either your white balance (WB) was off, or the yellow cast was done in post processing (PP).
#5: Is super grainy. Do you have a tripod? If so, try turning the ISO down and leaving the shutter open longer. The high ISO is what causes the grain. Keep in mind, however, that the longer the shutter's open, the more chance for motion blur there is. Tripods are a necessity for low light.
My best recommendation is to read up on those concepts I listed above, then go out and try applying them. Post the results and we'll let you know what's good and what's bad.
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