まず電車に30分乗って、その後にバスに45分乗りますって英語でなんて言うの？

"First" is the way to talk about beginning of a set of actions. You "take" public transportation so you can say "take a train" or "take a bus." I hope that this helps :)

When listing a number of activities or planning a timetable, you may explain the sequence of events by saying: "A is followed by B; B is follwed by C..." etc

When a journey has two or more 'legs' this mean that there are multiple parts to the journey. For example if I am flying from London to Tokyo and I have to swap flights at Hong Kong, this journey has two legs.

When talking about getting to a place or work by travelling then this is called to 'commute' so you can say 'to get to work' or 'to commute to work' To take a train for 30 minutes and then a bus for 45 minutes' explains how you get there and how long it takes

If you were asked by someone how you commute to work, that person is asking you what form of transport gets you to your workplace. You could use the above example as a more fuller explanation. Notice that you are first confirming what type of transport you take during your commute (e.g., "train " and "bus"). These are two very popular forms of transport for commuting. Then, you begin both the second and third sentence with a "linking word," also called a "transition word" ("First," which implies an immediate action is taking place and "Next," which implies a further action taking place in the sequence). Both these sentences are short and to the point. You will notice when writing this, that a comma follows each linking word. This is important in the structure of the sentence and when spoken too, as you need to provide a small pause after the comma and before the word that follows. This rule will help the flow and diction of your pronunciation. The time value used (e.g., "30-minute" and "45-minute") is the approximate time or duration each leg of your journey ("commute") takes you, each time you go to work.

Sometimes getting to work is a long process, to explain your route to work, use the sentences above. There are many different routes taken by different modes of transport, some are faster than others and others take special routes like trains. Trains use special tracks to travel on wheres buses use roads to travel. Consists: is made up of.

The verb 'have' used in this context means to experience, so we're saying that we experience those journey times. A 'journey' is the act of travelling from one place to another when it is used as a noun like this, so it means the same as saying a ride or a trip. 'Followed by' indicates that the next thing in the list is coming up. So in this case the train journey is first, and the bus journey is after that.