Hey there. I imagine you're talking about buying individual bonds? This is a strategy that, for the most part among retail investors, is not a popular one, due to the presence of bond funds.
For example, you can buy a portfolio of hundreds of BBB rated Canadian corporate bonds with maturities of 1-30 years in the click of a button via XHB.TO.
But if you're looking to buy bonds direct, it kind of depends on your brokerage. For example, for me being with Qtrade I would simply log in, select order, fixed income, and view the fixed income temrinal to make a selection. It lists the coupon dates, maturities, payment dates, current buy and ask orders, and the rating of the bond.
If you provide what brokerage you are with, I could probably give you some better direction.