Okay you want a real critique?
1. You have 4 lines of text and 3 different fonts. Basic amateur mistake, choose a font, maybe 2 and that's it. More isn't better when it comes to fonts.
2. If you insist on bending that tag line around corners then at least place them right. The top one should be above the alien in the upper left corner, not below it.
3. Again, if you insist on keeping the extrusion on PLANI (what is that?) then make it shallower.
4. Why do you have the super duper thing twice, in different styles and different capitalization? Lose the bottom one entirely.
5. Designed by Vas... the day any client lets you put a byline on a product advertisement that large is the day I fly to the moon by flapping my arms.
6. What are those icons in the grey bar on the right? For that matter what is this poster for? Unless there is some Indian thing I'm not aware of the poster doesn't give me any clue what I am looking at and that doesn't make for very good advertising, which is the ultimate goal of a poster.
7. Lose the glow around the main alien.
Overall in all honesty your lack of experience shows and my guess is you're young too. One of the first things people with little experience do is look at a piece of software and go "ooooh it can do this!! and it can do that! and look at all these cool colours and fonts!!!!"
Don't fall into that trap. Take your time, look around some of the work on this forum and see what looks good to you. Take a look around your town, at other posters and advertisements and see what the professionals are really doing.
I'm not saying give up and I am not being mean. A first attempt a few months into learning software isn't likely to be good and unfortunately there is too much wrong with yours to be considered good. That just means take the time and learn more and keep trying.
I ran into this when computers first started becoming cheap, everyone with Word became their own designer... what a clusterfuck >.< flyers with 30 colours, 40 fonts, brutal clipart and yay Word doesn't even do colour separations lol.