An easy way to incorporate icons is to use the icon classes:
<span class="icon-NAME"></span>
You could customize the colors by changing the font color in the CSS:
<span class="icon-arrow-down" style="color:red"></span>
Here are the available icons I've been able to find:
icon-add
icon-add-column
icon-addTag
icon-admin
icon-archive
icon-arrow-down
icon-arrow-left
icon-arrow-right
icon-arrow-up
icon-attachment
icon-back
icon-bars
icon-bell
icon-blocked
icon-board
icon-box
icon-calendar
icon-cancel
icon-change-set
icon-chat
icon-chevron-down
icon-chevron-left
icon-chevron-right
icon-chevron-up
icon-children
icon-circle
icon-close
icon-collapse
icon-color
icon-comment
icon-cone
icon-cross
icon-dashboard
icon-defect
icon-defectSuite
icon-delete
icon-deploy
icon-donut
icon-dots
icon-down
icon-down_full
icon-down_hollow
icon-download
icon-drag
icon-dropdown
icon-edit
icon-embed
icon-empty
icon-enlarge
icon-expand
icon-export
icon-favorite
icon-feedback
icon-file
icon-filter
icon-fiveDots
icon-flag
icon-folder
icon-full-arrow-down
icon-full-arrow-left
icon-full-arrow-right
icon-full-arrow-up
icon-gear
icon-graph
icon-grid
icon-help
icon-hierarchy
icon-history
icon-home
icon-hourglass
icon-idea
icon-images
icon-infinity
icon-info
icon-info-circle
icon-leaf
icon-leave
icon-left
icon-line
icon-link
icon-lock
icon-lock-open
icon-mail
icon-minus
icon-more
icon-next
icon-none
icon-not-favorite
icon-ok
icon-partial
icon-pie
icon-plus
icon-popup
icon-portfolio
icon-post
icon-predecessor
icon-previous
icon-print
icon-program
icon-progress
icon-question
icon-ready
icon-recycle
icon-refresh
icon-reply-all
icon-right
icon-right_full
icon-right_hollow
icon-rss
icon-save
icon-scope-down
icon-scope-up
icon-scope-up-down
icon-search
icon-setup
icon-share
icon-shrink
icon-small-chevron-down
icon-small-chevron-left
icon-small-chevron-right
icon-small-chevron-up
icon-snapshot
icon-split
icon-square
icon-story
icon-successor
icon-tag
icon-task
icon-test
icon-test-run
icon-testCase
icon-testSet
icon-threeDots
icon-thumbs-down
icon-thumbs-up
icon-to-do
icon-triangle
icon-up
icon-upload
icon-user
icon-user-add
icon-users
icon-visible
icon-warning
icon-workspace