well it looks normal enough. Look between you motherboard and the case to see if theres anything in the way, if there is carefully use a toothpick (or other non-metal object) to remove whats in the way.
If your mother boards too close to the casing look for the screws attaching the motherboard to the case, just lightly unscrew them and move the motherboard to a good spot and lightly retughten them.
If neither of those are the case (or theres nothing obstructing the metal plate) just force the card in, with my GF2 I had to put about 60% of my weight on the card. If you try this watch the card, they can crack if too much pressure is applied.
if you want to go with a purely safe way just cut 1/3rd of the metal off the plate on the bottom and see if she'll slide in.
Do eveything slowly and don't rush. Most first-time installers rush through stuff and aren't careful with the equipement.