Hi
Here are some snippet that will help
RichEdit1->SelStart=RichEdit1->Text.Length(); //or -1
RichEdit1->SelAttributes->Color=clOlive;
RichEdit1->SelText="red";
RichEdit1->SelStart=RichEdit1->Text.Length(); //or -1
RichEdit1->SelAttributes->Color=clBlue;
RichEdit1->SelText="blue";
//Set Color back
RichEdit1->SelAttributes->Color=clBlack;
and
TFontStyles FontStyle;
FontStyle << fsBold << fsItalic;
// Normal Red text
RichEdit1->SelAttributes->Color = clRed;
RichEdit1->Lines->Add("Some Normal Red Text"

;
// Bold, Italic, Purple text
FontStyle << fsBold << fsItalic;
RichEdit1->SelAttributes->Color = clPurple;
RichEdit1->SelAttributes->Style = FontStyle;
RichEdit1->Lines->Add("Some Bold, Italic, Purple Text"

;
// Normal Black text
FontStyle >> fsBold >> fsItalic;
RichEdit1->SelAttributes->Color = clBlack;
RichEdit1->SelAttributes->Style = FontStyle;
RichEdit1->Lines->Add("Some Normal Black Text"

;