Having landing gear gives you the best of both worlds, because you can take off or hand launch. Up to you! A plane without landing gear, oddly enough, restricts you to just hand launching.
If you’re on concrete, tarmac, smooth gravel or very short grass then a take off is easy. If you’re on longer grass or a very rough surface then your airplane might struggle to get the speed it needs to to get airborne.
In the same context, the size of your airplane’s wheels is also another deciding factor. Larger diameter wheels can cope better with more difficult surfaces, whereas smaller diameter wheels are only good for smooth, harder surfaces.
Finally, you just might prefer to hand launch your plane, even though it’s got an undercarriage and you’re flying from a smooth surface. Nothing wrong with that, if that’s what you’re most comfortable with!
The Take off:
To perform a take off, smoothly increase motor power to full (take between one and two seconds to move the stick fully forward) and let the airplane accelerate along the ground. It’s probable that you’ll need to use rudder to keep the plane going in a straight line, don’t let it veer off to the left or right. Keep it straight all the time.
Once you’re at full power and the plane is accelerating along the ground, gently apply a small amount of up elevator to aid the plane off the ground. Don’t yank back on the stick, just pull back smoothly. If you apply too much too quickly, and the plane hasn’t yet reached flying speed, it can get airborne too early and with too steep a climb rate, and stall. Not good!