If they are too big to post, then they are high quality!!!
Here is how to compress without losing quality.
Take your image open it on the computer and then do a save as
choose type jpg then there should be an option or more or compression depending on the program.
Here is how much to compress on various scales:
1 to 100 (100 being LEAST) 78 would be where you would want it
1 to 100 (1 being LEAST) 22 would be where you would want it
On a scale of 1 to 10, 10 being LEAST compression pick 7 or 8.
On a scale of 1 to 10, 1 being LEAST compression pick 2 or 3.
In photoshop, 12 is max. 8 or 9 is most should compress.
You get the idea. An uncompressed image should only be compressed at most 22% before it starts to lose resolution.