Help with cables please.
 

Ok guys you have to forgive me. I'm new at this. I would like to replace my wife's 10 speeds cables there original and a little rust. I'm just unsure how to buy these. How does it come? Is there a tool to crimp on new ends on the outer cable cover part. I need to know how you do this? and what to buy. This is an old miyata 10 speed from the early 90's So they should be replaced. It nice for her it's her older childhood bike. So I'm happy to fix it up for her.

You can buy brake and derailleur cables and housing at any bike shop. They aren't the same as the cables have different end fittings and typically derailleur cable is a bit thinner. Brake housing is larger in diameter and made differently (spiral wound) than derailleur housing. For both, buy lined housing and stainless steel cables. The end fittings (aka ferrules) are typically just slip on so no crimping is needed.

There are premade housing and cable kits available but they tend to be more costly than bulk housing bought by the fool and individual cables.

Does the brand name matter? Meaning they might use different ends that may not fit in brake handles or shifter.

Derailleur cables have two different end fittings, one fits Shimano and SRAM, the other (smaller) fits Campy. The probability of your wife's bike being Campy is nearly zero. Brake cables also have two different fittings, one for road levers and one for MTB. Many cables come double ended and you just cut off the unneeded end.

Take the bike to a bike shop and they will be sure you get the correct cables and housing.