anyone know how to make obsidian in minecraft?

No diamond pickaxe yet? You can still get a portal. Build a mould out of cobble where you want the frame, pour lava into each slot, then pour water over it so it hardens in place. Pick the water back up after each one so it doesn't wash the lava away.

water source running onto a lava source makes obsidian, and you need a diamond or netherite pickaxe to pick it up. if you're getting cobblestone instead, the lava was flowing rather than a source block.