The only way you can learn how to use any new tool is by trying to use them. Until you try and fail many times you will not know the capabilities and pitfalls of you and this new machine for you. Play with this machine with some tracks (files) that you don't care if they are lost first. Learn what it takes to properly archive your raw files before attempting to assemble them into a finished CD. Make a few practice finished CDs of some of your practice recordings and play them back on your home sound system (not through the Tascam) to evaluate the differences in your final mixes. Also accept the idea that you've yet to master this instrument and all of its nuances.
Good Luck and Happy Recording
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"Don't disturb my circles." translation of Archimedes last words