i have a shifting question. how can you shift from the small front gear to the big gear easier? and vice versa?

in what rear cog(s) is it better for shifting the front rings?

Just ease up on your pedal stroke while shifting.

You need to let us know what sort of shifting system you have on your bike.
For example, with modern Shimano STI shifters, you should be able to flip it into the big ring while standing, and pedaling under full force.

it's the new 105 10sp, i just couldnt get it to go from the big ring to the small ring.

should i go to the middle rear cogs to get it shift easier?

it's the new 105 10sp, i just couldnt get it to go from the big ring to the small ring.

should i go to the middle rear cogs to get it shift easier?
It should shift fine in any rear position. If it won't, it's not adjusted correctly. Either learn yourself by looking at the parktool.com web site and asking questions or take it to the shop. - TF

^hmmm...ok.

it's the new 105 10sp, i just couldnt get it to go from the big ring to the small ring.

should i go to the middle rear cogs to get it shift easier?

If you have the chain on the big front gear, and the big rear gear, you've taken most of the slack out of the system and it can get testy when down shifting the front- so yes, shift the cassette more towards the middle before you get to that position.