Locate the (4) R4 Bearings and (8) Bearing Covers.

Start by laying a sleeve half on the table, face up. Set an R4ZZ bearing into it and firmly press it into place.

Now set another sleeve half on the table and press the R4ZZ bearing and sleeve into the new sleeve half to complete the carriage wheel.

Repeat this process for the (3) remaining bearings.

A video demonstration can be found here.