So, I have a bunch of things I need clearing up...

1.When people say "lets jam in the e minor pentatonic" do you have to play only the notes in the e minor pentatonic scale? or does it mean explore the fret board where ever you want but just go back to the MP scale sometimes?

2.Do you have to use a scale to solo or can you just make a soloS from what you feel and use scales to help out sometimes? (meaning you don't have to play only notes in that scale)

3.How do you practise chord construction and what are some good sites that help you on it?

4.when you make a solo do you have to know every single note on the fretboard or do you just play whatever?

5.how do you do you make a solo?

sorry for the many stupid questions...
1. well, the people i usually play with just tell me a key but just the relative minor of it (like Ami for C) ...when someone tells you to play in a pentatonic, do they play a riff or chords? well, it depends on how strictly you want to work off the pentatonic, or what kind of sound you wanna aim for...usually the song will on the root of the pentatonic, but not always, but usually

2. well, i'll keep it simple since it seems that you dont know too much about keys and such (not to offend)....it'll be the better thing to do to improvise (solo) within the boundaries of a certain key (scale) of that particular, and if you want, with an occasional note that is out of the key (an "accidental" note), but do not bring too much attention to that accident. if you use too much, the solo will sound lost and confused and people will notice that something is not right...ears can tell

3. i say learn about how to creat a triad (chord) by taking the I III V (notes) of the scale (say C) the I = C, III = E, V = G = MAKES a C chord! and i dont know any sites, sorry, i can show you all i know tho, if you want

4. Yes you do, its better that way. hard work but worth it

5. by having an imagination and just mess around with certain keys and chords and think of a certain melody(s) from a tune you like and use it in a solo (but converted into YOUR key) and just mess around with it...it takes time to become better

any questions, just ask!
The notes depend on the context of what your playing. Some notes that seem to be out of key and the chordal tones, can be looked at as creating tension. But seeing as you are saying jamming on minor pentatonic, I will just assume that you are doing some blues rock style playing with a basic progression. In this case, most people will just stick to the chord tones and scales instead of thinking outside the box. Or if by explore, you mean that you only know the basic box position. For that just learn the other positions and forget about tensions. You don't have to use scales at all if you are fluent with things like arpeggios that you can follow the chord changes with. But most advise to mix both arpeggios and scales into your improv.
One of the biggest things that helps people understand chord construction is a piano. Everything is very visual and it is easy to understand. Using that along with a basic theory book will help you understand.
How to make a solo is one of broadest questions in music you can ask
When I solo I think of a scale as more of a guide than a limitation. If you can use your creative mind, you can go outside of the scale (chromatic runs being an example) but it has to flow with everything else. It also depends what genre you're in, a lot of chromatic runs would sound better in metal than classic rock.