I need to replace my rim spokes for Schwinn 28" men and women's bikes which size do I order? and where can I order them? thanks
The easiest way to find the correct length is to measure the existing spokes. Note that the front and rear typically use different lengths and rear has different lengths on left and right side. If there is a disc brake in front, the different sides may have different lengths too. The nipple threads are usually same size, but the middle of the spoke may be thinner, again the easiest way is to use a vernier caliper to measure the thickness.
Shopping questions are frowned upon here, so I'll just leave a hint that spokes are available in most specialized bicycle stores, both online and brick and mortar. You can sure find one.
Replacing the spokes is not very advanced skill but takes some patience at first. There are many instructions online, read at least one set before doing anything and decide whether this is something you want to attempt.