On SketchUp Free, you can download your model file to you computer using the menu at the folder icon in the upper right.
You can then upload the model to a post on this forum either by using the upload button at the top of the reply edit window or by drag-n-drop the file onto the reply window.
What are the gross dimensions of the objects you are modeling? If they are either very small or very large that could be contributing to your troubles. You can measure them using the tape measure tool from the icon menu at the left of the screen.
Regarding the component, did you mean the one by jaspirian, second from bottom in your screenshot, or the bottom one by zaqwertyyuio (or yet another)? I ask because the bottom one is not a phillips screw head.
Both of those are not particularly good models and may be causing trouble for you. The j one is just the hollow shell of a screw head, and is set to glue its outer edge at right angles to vertical surfaces. The z one is grossly misscaled, being about 3 feet tall! As a beginner, you wouldn’t know, but there is no quality control on the 3DWarehouse and many of the models there are either very poorly made (like these) or are grossly over-detailed for use as anything except a single standalone object.