Grab that 16" electric and get a couple of NEW chains for it ! If the wood is soft, it should go through it like butter ! The biggest mistake rookies make is pushing the saw. Let tha saw and chain do the work. If it is not cutting good, replace the chain with a spare.
The second biggest mistake rookies make with a tree laying on the ground is to try and cut it as it sits. You likely will severely dull the chain ! You really need a "log lifter" like this
Start at the top of the tree and work down. Try to only cut the part of the tree that is supported at one end
(by the log lifter or something else) so that gravity will make the end fall off. If you have to cut in between 2 support points, the saw will bind if you start from the top. Cut
UP from underneath about 1/3 - 1/2 of the way. Now you can start to cut from the top, but you are better of by starting with a wedge cut and then progressively make it deeper.