Start with a saturated cyclopentane ring (a five member saturated carbon ring).  
1. Designate the carbon that bears the side-chain (the carbonyl group) as C-1 of the ring.  
2. Attach a carbonyl carbon (-C(=O)-) directly to C-1.  
3. On that carbonyl carbon place:  
   a. A methoxy group (-O-CH3) to form a methyl ester.  
   b. The ring connection to C-1 just mentioned.   
4. On ring carbon C-3, attach two methyl groups (gem-dimethyl).  
5. All other ring positions are unsubstituted and fully saturated; no stereocenters or double-bond geometry need specification.