Drum brake installation troubles...

The primary shoe goes to the front.(short shoe) The shoes are not side specific. If You're only having problems in the rear it's usually e-brake related.
If the shoes are tight to the pivot pin on the top and tight against the collapsed adjuster on the bottom the drum should slide on. (if the shoes and the drum are correct.) Grab your tape measure and measure the shoes and the drum diameter. The drums should be slightly larger of course.