The instruction card included in your package shows the 2 methods to connect the 'male tab' into the 'female slot'.
Soak or run the tabs and slots under the sink tap in warm water or heat from hair dryer-  until the tabs are very soft-try inserting again.
If you are still having problems 'THINK of the male tab as a 'fishing hook' that you are 'inserting" itn a fishing hook motion. (Or a jewelry clasp motion).  Repeat until all the 8 connections are completed.  Once done use cold water to harden the plastic or allow to cool at room temperature for 3 minutes- this is to 'secure' each joint.
*If you are still having problems we have a lengthy step-by-step video on our FloraGUPPY YOUTUBE channel, search 'ASSEMBLY'