first off, you are in a great state for only 1 year of experience. you know all the notes on the fretboard, you understand triads and 4 note chords and you can improv over a chord. so at the end of the day youre in a great level of understanding in the amount of time youve spent learning to play guitar.
here is some advice, it may be all over the place bc i truly dont know EXACTLY where you are with your guitar experience, so hope it helps your improv sound as good as possible..
You can play over a backing track with the barre chords, C and F. we know both those chords are in the key of C so that means we can use the notes from the C major scale on both of these chords and itll sound good.
I'll start with some easy advice first: If youre fairly new to improving then start simply by playing the scale up and down... getting to know the scale and know the sound. try to keep in time.
next thing you can try is to, 'speak in sentences' - try playing the guitar as if youre 'speaking'. dont make the sentences too long and stop once in awhile to 'breathe'. One lick after the other.
what works even better is if you repeat some parts a few times, so that it starts making more sense to the listener or to yourself.
play short sentence that make sense. try to incorporate the same ideas from the first part, in to the second part. then repeat the first part again, and play the second apart again. so now youve made connections with the things you played and everything makes sense. 1 rule of thumb = its better to play less than to play too much.
tip 3, licks! memorize some licks. theyre great to remember and use in your own imporv. learn alot of solos.
tip 4, listen to your own playing. record yourself and listen to yourself. so you can take as step back and hear the bigger story in your improvisation. it will help you make them sound coherent.
tip 5, make sure you learn your theory, very well. if you dont know what to play that often comes down to a lack of theory. if you hear what chords are being played you may be able to instantly get an idea of what scales or licks to use. when you nail donw your music theory itll help you link what scales you want to play for the chords playing.
ADVANCED TIP. this one may be more suited to help you than the previous tips. TARGET NOTES
Use target notes from the chord that is being played. maybe just try to play over 2 barre chords C & F. those chords sound fairly different. so the goal here would be to emphasize notes from the chord that is playing at the moment and you can make sure your improv is more interesting. so you would play diff notes on the c major chord than you would on the F major chord. you can do this via arpeggios or the caged system.
so you know C barre chord in the 8th position with the root on the 6th string and the F barre chord, also in the 8th position (with the root on the 5th string).
So sticking to the top 3 strings, to make it easier, the target notes for C would be: the 9th fret on the 3rd string and the 8th fret on both the 1st and 2nd strings. So any of those notes would sound like a 'home' note on the C chord.
The target notes for F would be: the 10th fret on both the 3rd and 2nd strings and 8th fret on the 1st string. so any of those notes would make a great 'home' note for the F chord.
So if you play a lick and end on a note that is from the chord being played itll sound nice.
So notes played from the chord that is playing will sound more consonant and without any tensions and if you play a note from outside of the chord it will sound like it needs to resolve back, so there IS tension. so play around with that.
but at the end of the day, the most important thing is to just HAVE FUN