if you have no experience then you best to start with LSL. is the easiest of all to learn
the LSL wiki/library is fairly comprehensive. Take some of the library scripts and experiment with them. to start with look for scripts that can be applied to a prim and changes it. color changes, texture changes and texture animations are good to start with. can get immediate feedback inworld when run the script. Then move on to particles and motion/flight/vehicle scripts. can take a vehicle/flight library script and drop it in a prim. sit on it and off you go - flying/moving. is quite fun to learn that way
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syntax-wise LSL is similar to C. so when move on to other languages like javascript and C# then will be kinda familiar
if you have WIn8.x then can look at Visual Studio Express Blend. can write javascript apps with that for Win8 Mod/Metro and XBox