Hi Carol,
If you are using Elements and wish to rotate an image this is the procedure based on Elements 7 and I'm sure later versions will be similar;
a) IMAGE / ROTATE / CUSTOM - You then type in degrees and direction.
OR
b) From the Tool bar select 'STRAIGHTEN' tool (two rectangles, one sloping) Place the cursor cross-hairs on the image and drag the line across. EG, if you have a sloping horizon place the cursor on it at the far left and draw across placing it on the horizon at the far right, hey presto, horizon is level.
For critical adjustment you can also place the 'GRID' on the image by selecting VIEW / GRID
Grahame