@wcarlsonM2NUS wrote:
...I don't understand sketchs 2 and 3. I don't see how they relate to the rest of the sketch...
sketches are related/linked to each other with projections from previous sketches (purple articles.) projections are one of the most important tools to use with sketches. if your not using them now is the time to study up. there are several types, and they are all useful.
turn on the visibility for dimensions for all there sketches so your screen looks like this-

DOUBLE CLICK on one of the DIMENSIONS, such as the one I have circled, and change it to a reasonable value. what do you observe? play around with all the dims and see what happens.
all the extrudes reference sketch articles using the START and EXTENT TYPE inputs in the extrude commands. the result is that you can look at the model like in the pic above to make adjustments instead of digging around in features in the timeline, which gets increasingly difficult as projects get bigger.
...I see you created half the sketch and then mirrored it for symmetricity. Ordinarily this would be great, but the holes on the other lug don't match.
then don't create holes that aren't mirrored till after the mirror feature. put them in a sketch and extrude/cut after in the same way the other sketches and extrudes where made.
You can use the sketches already created, or create new ones. I would still group sketches at the beginning of the timeline, and I would still put them on origin planes and not the faces of the solid.