A schematic of the solution is shown below. The information from the question is given in black. Deductions directly from this information are given in red. Points that provide potential key information are shown by green arrows which leads to the structures which are linked via the blue arrows to show the path required to work them all out. There are, of course, other possible thought pathways.

The keys here are (1) getting the molecular formula of A and (2) realising A has 4 types of H, (3) the names of the products and (4) realising how to get the 2 C₅ alkenes C and D from the intial ozonolysis data. Note that this also confirms that A is C₅.
This means A has to be 2-methylbutane and then B, C, D, E and F come from that. Details of G are worked out from (1) hydrogenation product gives skeleton (2) ozonolysis products define C=C locations, alternatively, use the Diels-Alder reaction that causes F to dimerise to give G.