I think Dave Richards will know of some good videos on moving objects. Basically you want to move it by grabbing at a sensible location. Go to move your component--say a chair and put the cursor so it snaps to a vertex at the bottom of the leg. Then when you move to the floor look to see the clue "On face" then you know you when you click to let go of the chair the point you started the move with will end up touching the face of the floor.
That's basically it grab things (usually components or groups) at the point which you want to touch or align to other objects.
The rotate tool is pretty straight forward. You need to learn to get the different orientations. The basics are orientation to the model xyz directions. If you hover the tool over the ground that will give you the orientation of Blue protractor. Then press "shift" key to keep that orientation. Move to the logical point of rotation (hopefully on a an object or the ground, but not required) and rotate your (pre-selected) object. There are many features to getting the orientations but that's the main idea.
Many videos at the SketchUp Trimble website for the basic tools. Also Aidan Chopras videos on Utube.
Here's one from a search, but I think it's a little old. The info right but there are probably better videos.
https://www.youtube.com/watch?v=2e095bSztLs