In Survival, large objects require you to place a scaffold first, then finish the project with a hammer and more materials.

Chop trees for logs and mine stone for building materials.

Switch between blocks in a "Block Group" (top-right symbol on some icons).

Use the Research List ( K ) to unlock more advanced blocks and tools as you progress.

Generally, try not to build higher than eight blocks without significant architectural support like archways or multiple columns.