On a pad or tablet, simply type in the BB code. Easy.
Type in:
[center][color=magenta][size=4][b][i] whatever [/i][/b][/size][/color][/center]
and you get
whatever
...and to quote just type
[quote=fred]copy of whatever[/quote]
becomes
Originally Posted by fred
copy of whatever
For an image use
[center][img]http://www.mike-wsm.org.uk/home01.jpg[/img][/center]
to see
Youtube tags are
[center][youtube]elevendigitcode[/youtube][/center]
.