I am very new to photography and Adobe. When I view my photos on my phone or on facebook, they look great, but when I put them into Lightroom they become very grainy. I have included pictures of what I am referring too. Is there a way to fix this? Is something off with the sizing of the image?
When I look at your screenshot, the thing that sticks out is that the LRC one is of low resolution. This is because it is only a preview of the image, not the image. In your computer, you are looking at the image and it will show full resolution.
I could write up a whole bunch of stuff but let me hand you off to a good summation of LRC's Preview generation. Let us know after you've digested this and let us know if this solves your problem.
One hint: in the text he mentions Catalog Settings. If you do not know where to find this, it will be uner the LRC menu just under LRC Preferences.