Hi mcdonald1687, hi folks.
Please, use the post title only to specify what is your question.
Then use the body of the post to give more details.
In this case, can you specify which tool is giving you problem.
Read the help about each tool to see how to enter precise values like a length for a line or a radius for a circle or sides lengths for a rectangle, etc.
Read the help about the user interface, more specifically about the Dimension Window (DW) also called Dimension Box. You will see that you do not have to click in it to enter a value, you just type and then press the RETURN key or the ENTER key to validate your value.
This box becomes active automatically when it is ready to accept a value. It will change from grey to white. White means that it is open.
Observe also the status bar (SB) below the model window and read each of the hints that SketchUp is giving you.
For example, after choosing the Line tool, the SB will show Ready. Then, after clicking to start the line, it will show Click endpoint or enter value. This means that you can click to start a line, move the mouse to establish the direction of the line and then, leave the mouse as it is and type 12 and press return to get a line that is 12 unit long. The unit being your defalut unit (feet, inch, meter, centimeter or millimeter). You can temporarily use another unit if you want. Forexample, if you use feet as default but want a line to be 35 meters long, you would enter 35m in the DW.
Just ideas.
Jean