Go back to the gravedigger and try talking to him again. You'll find out that he doesn't need the shovel anymore, so you may as well keep it. Ask him a few other questions, concerning the Godalming Manor, the Other Entrance and the Watchman. You'll find out that you should look for some additional clues near the main crypt of the cemetery. End this conversation and go back to the area with the shed. Choose the passageway near the bushes (screen) and use the stairs to get down to a lower level.
You'll end up standing next to a large tomb with two angels "guarding" the entrance. Obviously you should consider taking a closer look at the angels, as well as the main gate. Listen to what Van Helsing has to say about it and read a new report which can now be found in your personal diary - The Crypt's Inscription. Press the right mouse button in order to open your inventory. Choose the metal bar (it's going to be highlighted) and close the inventory window. You should notice the icon of the metal bar at the top right corner of the screen. It means this item is active. Click on other metal bars and you'll be able to stretch them.
Now you will have to combine two items from your inventory. Start off by opening it. Click on the matches and drag them to an icon of a lantern. You will end up having a lit lantern. Now you will have to combine the lantern with a shovel which you have found in the shed. Choose this new object and close the inventory.
Use the lamp on an opening (where you were able to stretch some of the bars). Van Helsing should automatically place the lamp inside the tomb. Your next challenge will be to read the inscriptions on the gravestone (screen). Click on the tomb and you'll be rewarded with a new document - Poem from the crypt. Make sure that you've read the poem (especially the second verse), because it contains important clues on how you should act next. You may close this window. Go back to the view with the angels.
Your next task will be to solve four riddles. All the puzzles are connected to angel statues which can be found throughout this entire area. The first statue of an angel is on your right, so you'll only have to go there (screen). Click on an angel and wait for the game to display a new screen. Read the inscription and familiarize yourself with a clue on how to solve this problem.
As you've probably noticed, there are some figures on the screen. Some of them represent angels and some of them represent demons. Start clicking on small icons located next to each figure. Choose K for demon (chalice icon) and choose L for angel (tear icon). Look at my screen if you're having some difficulties finding the differences between angels and demons. End this puzzle by clicking on angel icon found in the upper left corner of the screen. You should hear some sounds (working machinery) which means you've been successful.
Now you should consider going back to the start area. Once you're there, proceed to the bottom of the screen. You can click on the statue right away (screen) or you can take some time by looking at the flowers. Just as before, you should consider reading a short description of the riddle.