I have been watching a lot of videos on youtube from the past one year and I have learnt a lot about guitar theory, fingerstyle techniques andei can even play many fingerstyle songs on guitar by watching tutorials. ...few days ago I tried to make an arrangement of my own.....I found the melody, the chord progression, the bass notes....but I cant figure out how I can use these elements and blend them together to make a full arrangement....I can make a raw arrangement by playing the bass notes and melody but how to add other notes to it and make it sound better ?.....
I'm not a guitarist, but generally when doing an arrangement, you do your melody and bass line. The you fill in with other notes from the chord. For example, if I'm filling out a measure where the melody is on E and the bass is on C, I might put another C and G in between to fill out the harmony. Now I have something like CCGE.
Rule of thumb: double the root (name of the chord) and put the rest of the chord notes in the middle. That will pretty much always sound good, if you have the right chord. Remember that if you're using a 7 chord you have 4 notes to work with.
Another important part of making a great arrangement is voice leading. The melody is usually done for you if you're doing an arrangement, but you can do what you want with the other voices. Think of each note in a chord as a separate voice, and make sure it "flows" nicely into the next note. I write my bottom voice first since it's usually the most audible, and you can do a walking bass or whatever rather than just playing the chord name as the lowest note. Then fill in the inner voices with the other notes of the chord, and make them sound good. A good music theory course will have you doing some part writing and teach you general rules of what to do with various notes.
The master of this type of thing is still Bach. Take a look at his violin partitas for ideas of how to use voiceleading with running notes, his fugues and inventions for polyphonic (independent voice) examples, and is chorales for how to move chords around. And they all sound cool on guitar too!