Is it ok for a beginner to learn to play riff and soloing ? I know i should get to know the chords by heart but just would like to learn to play some awesome riffs and solos. I really like arch enemy "Behind the smile" cool riff and solo of that song.

THis is advanced stuff and not sure if an absolute beginner can pull this off. I know it won't make me a great guitar player
Of course it is. Dispite the fact that you should still learn the major and minor chords, there's no reason why you shouldn't learn riffs. After all, the first thing that everybody learns on guitar is almost allways the Smoke On The Water riff by Deep Purple.

Gozd in gora poj,
silen ženimo hrup,
uboga gmajna, le vpup, le vkup,
le vkup, le vkup z menoj,
staro pravdo v mrak tulimo,
da se pretulimo skozi to zimo
im basically a beginner and i have tried to pull off songs i cant play and you are right it wont make you a great player but its experience! I personally dont know the song but there is nothing wrong with trying! Ive tried and failed several times to play songs but it just gives you something to aim for in your practice! A year ago i tried to play the clean and acoustic for stairway to heaven and failed epically, but 2 weeks ago i thought 'i'll give that another go now after a year playing and practicing skills' and it seemed easy!

So as long as you dont stop playing the simpler stuff and if you cant play the song you move on there is no bad in trying to play your favorite songs!
I think you should learn your favorite song,it keeps practice and playing fun.We play guitar for fun anyway don't we?I personally spend part of my practice time learning songs and riffs,and then I will work on a new chord or something.
For me, I started with riffs, then learned the chords and everything else. Because really, riffs use techniques which you develop by playing them alot. Still need to learn the chords and scales and everything else, though