How can we effectively design a web layout using Adobe Photoshop ?

Photoshop is a raster image editor.  It's not sufficient for creating web UI/UX experiences.

Until recently, XD was Adobe's go to UI/UX design app.  But XD development stopped after Adobe announced intent to acquire Figma.

Try Figma free below.

https://www.figma.com/figma-vs-adobe-xd/

Form without function is nothing to a web developer.  Best advice, find 5 or 6 working websites or website Themes to use as examples. Tell your developer what you like and dislike about each one.

ANSWER THESE QUESTIONS:

• What's the purpose/goal of your site?
• Who is your main target user?
• List all functionality you require  -- be specific.
• In how many languages will content be offered?
• How do you envision users interacting with the site from mobile, tablet and desktop devices?
• How much web experience do you have with coding/programming, accessibility, SEO, social media & web content creation?
• When the site is completed, who will maintain it -- you or a dedicated team of web experts?

Once your developer understands what nuts & bolts are needed, then you can work on eye candy  -- color pallets, branding images, typography & layout options.

Good luck.

Will they use Captivate for the developing? You posted this in the Captivate forum, hence my question.

I have been working with companies where the images were provided in PSDs often. I will wait on your answer about Captivate to provide more information. However my answer will not be valid for the new version 12 because there is no longer a real collaboration between that version and Photoshop as is the case for all previous versions. Have a look at:

https://blog.lilybiri.com/roundtripping-with-adobe-photoshop-in-2020