One approach to writing a website Welcome Message is to provide a brief statement of the purpose of your website:-

• Tell your users in as few words as possible what they can find and achieve on your website.  Express this in terms that the end user can understand, even if they are unfamiliar with what you offer.
• Avoid marketing “fluff”. Avoid using a statement that sounds like a corporate mission statement, which is self-promotional or essentially unhelpful to the user.
• Keep your welcome statement brief and concise.  Don’t waste your user’s time.
• Try using a bullet point list – this helps readability – users can grasp the contents more easily.