How do I make arrows and colored squares using Chesstempo's viewer? I am using Anki to study chess. I use Chesstempo's viewer. My question is: How can I make arrows and squares with color on the board?
I do not think that it is currently possible. Here is a list of features, and while a couple are close, that looks like a future enhancement. Here is a link to the original source.

Features in current version

Multiple games per PGN file
Multiple boards per page
PGN comments/annotations
Recursive Annotation Variations (i.e. alternative lines)
FEN tag supported for arbitrary starting positions
Support for subset of Numerical Annotation Glyphs (NAGs, e.g. ? !?)
Multiple board size and piece styles
Option for automatically playing through all game moves
Alternative move display formats
CSS controlled layout
Animated piece moves
Optional Row and column labels
Drag and drop piece moves (to make next move in game)
**Optional Highlighting of from/to squares
Optional Highlighting of valid squares when dragging pieces**
Display of taken pieces
Read moves from PGN file on server or embed PGN directly into webpage


Features to be added in future versions

Crosstable support
**Visual hints such as move direction arrows etc**
Record moves mode with PGN output
Allow embedded board snapshots in move display
Configurable Board flipping (current version auto-flips if first mover is black).