Re: how did the oceans on some of the planet

There's not a lot that's directly known about this, to be honest with 
you.  Images of Mars very strongly suggest the presence of a lot of liquid 
water at some time in the past, but it's not sure that Mars ever had 
oceans as we do on Earth.  It is pretty certain that Venus and Mercury 
never had oceans because they're too hot to have liquid water.  The gas 
giants, Jupiter, Saturn, Uranus, and Neptune are likely to have a lot of 
water, but all as water vapor in their atmospheres, and Pluto is just too 
cold to have had liquid water.  Europa (a moon of Jupiter) may have a 
liquid ocean, but this is likely to be buried beneath a thick ice cover.

As far as Mars goes, right now it is thought that it never had large 
amounts of liquid water in the form of oceans.  It is thought more likely 
that Mars once had huge underground aquifers that held large amounts of 
water.  At some time, for an unknown reason, some of these aquifers seem 
to have discharged their water to the surface, causing massive flooding 
and carving all of the features we now see.  To the best of my knowledge, 
nobody knows what might have caused such a catastrophe.  After flowing for 
up to hundreds of miles, the water would have formed large, temporary 
lakes before soaking into the ground again or evaporating.  Some people 
think that this water is all still on Mars, just frozen below the 
surface.  Others think that water molecules present as vapor in the 
atmosphere would have been broken apart into hydrogen and oxygen by solar 
and cosmic radiation, with the gases being lost to space over time.

To find out more on this topic, I'd suggest trying the NASA WWW page 
(www.nasa.gov) and looking for information under Mars.  Also, believe it 
or not, Kim Stanley Robinson's Mars books (Red Mars, Green Mars, Blue 
Mars) have a lot of very good scientific information about Mars and have 
been highly praised by planetary scientists as well as being excellent 
science fiction.  Good luck!