Pretty easy.
Hardest part is probably deciding what lube to use.
A bunch of options out there. The Moco (used to?) sell a "
special" lube in it`s own little applicator.
Other companies make "specialized" cable lubes as well.
Have heard of people using anything from 3 in 1 Oil to liquid graphite.

Always wondered how well some of the lubes designed for firearms would work.
Two notes of caution.
1) Whatever you use. It should be a
very light viscosity.
A heavier weight can attract and hold dust and dirt more readily. As well as get stiff in cold weather. This will gum up the cable.
2) While I do`t think they make Teflon coated throttle cables.
Never use any sort of lube on one that is.
And. While you are at it. Would probably not hurt to lube the clutch cable. As long as it is
not Teflon coated.
If after oiling the cable the situation does not improve. There is a chance one or the other cable has started to fray. A strand of the cable has cracked or broken and started to unwind. If that is the case then the cable(s) need replaced.