Do u have any tips in making your own riff ?

I would start with the tune of the chorus then, just he basic notes. Play the notes, then add the chords around the the notes. Try different fingerings and effects around it. Also, depending on the style of the song you're putting together, try different picking and strumming patterns around it. It also helps to sing along while you play, that way you can hear how it will go with the feel and mood of the lyrics. Good luck with it!