http://www.codeproject.com/cs/miscctrl/alphablendtextbox.asp

ここにあるコントロールのインストール法が分かりません。ツールバーってどこですか？
誰か教えてください。

To use this control from the Visual Studio designer,
simply right click on the tool bar and choose "Add/Remove Items" and then click "
Browse" and browse to the AlphaBlendTextBox.dll file.
After doing this, the AlphaBlendTextBox control should appear in your tool bar (under "My User Controls" if you have VS2003). Now you can drag the control to a form and use it just like the original TextBox control.
The control has a new property named BackAlpha that will allow you to set the control's background alphablend value.
The range is 0 for transparent, 255 for opaque, or in between for translucent.